One factor that contributes to adolescent positive mental health is active engagement. Engagement is defined as any activity that is initiated to attain an outcome. In general, two forms of activities exist that correspond with engagement: solitary, non-structured, and non-cooperative pursuits, often without adult supervision (e.g., playing video games, watching television) and highly structured, collaborative activities that are under the guidance of a competent set of adults (i.e., structured extracurricular activities, or SEAs). Although large amounts of time spent in unstructured activities is related to negative psychosocial outcomes, participation in SEAs has been related to a variety of positive outcomes for students. This paper reviews current research regarding adolescent participation in SEAs and its effects on academic and personal-social variables (i.e., self-concept, life satisfaction), as well as potential preventive effects for youths considered to be "at-risk" for negative developmental outcomes. The paper also examines research investigating the potential benefits and shortcomings of different types of SEAs. Finally, suggestions for future research and school-based preventive intervention are presented.